DYSENTERY BACILLI 121 



sterile needle and several drops or more of blood obtained in a sterile capillary 

 tube. A i : 10 dilution of the serum is made with normal salt solution. 



One drop of this i : 10 dilution of serum is mixed with i drop of a 2 4-hour - 

 old bouillon culture of a known dysentery bacillus and placed on a hanging- 

 drop slide and examined for agglutination, as in making a Widal test. 



If a negative result is obtained the test should be repeated with as many 

 different types of dysentery bacilli as one may have at hand. 



A positive reaction establishes the diagnosis. Negative reactions do not 

 indicate the absence of bacillary dysentery unless made with all the different 

 types of dysentery bacilli. It is to be remembered that agglutinins are not 

 present in the blood during the first few days of the disease and that bacteria 

 cannot be isolated from the stools after the third week of the disease. 



